RF modules typically require RFI (radio frequency interference) shielding in order to function properly. The shielding reduces interference not only from external sources, but also from various functional blocks within the RF module. A typical prior art RF shield is a five-sided metal enclosure, known as a can, that is mounted on the PCB (printed circuit board) and fits over the shielded components. The can is often soldered to the board at the same time as the electronic components on the board. However, repairing misplaced components and fixing other problems underneath a soldered RF shield is impossible without removing the shield. Removing a soldered shield is an expensive and time consuming task that can cause additional damage to the assembly and/or possibly remove the original fault leading to no-trouble-found defects. The access problem with soldered can RF shields can be avoided by using shields that are easily opened when repair work is necessary.
Such openable shields are known and in the past have included snap-on shields, fences and shields with removable lids. All of the known openable shields are limited to use in environments where there is plenty of space on the PCB to incorporate such designs. As PCB's get ever smaller and more densely packed, there is no longer room for the bulky openable shields of the prior art. One alternative to openable shields is to use standard cans that cannot be opened and simply scrap any units having defects. This is usually not cost effective, especially with new designs that may have low yields of non-defective units in the early stages of production. Another alternative is to solder all the components except the shield, test the board, fix any problems found and then solder the standard can onto the board. This has the drawback of effectively cutting the throughput of a reflow soldering oven in half or requiring the purchase of a second oven and a line to support it. Moreover, every additional pass through the oven may significantly degrade the lifetime performance of the module, and it becomes more difficult to place the shields on reflowed solder pads. Also, an additional pass through a reflow oven may render a previously functional unit non-functional due to components moving during the process. In some modules component placement and packaging are so dense that it is virtually impossible to reach in with a soldering iron to reflow a shield. Furthermore, once the shield is replaced it must be coplanar with the PCB in order to fit within the module's covers. These alternatives to an openable shield are not attractive so the need is evident for an openable shield that requires no more space than that used by a standard non-openable can type RF shield.